3D printing novel porous granule-type bioceramics via magnesium tuning biological performances beneficial for implantation and clinical translation

The requirement for bone grafts needed for filling bone defect and fracture is increasing annually due to global ageing and a great amount of bone trauma cases, whereas the conventional bioceramic implants is suboptimal for bone regeneration and inconvenient for implantation operation. Here we describe the 3D printed granule-type bioceramics and evaluate the porous architectures and biological performances of two types of Mg-mediating silicate bioceramics. The 6 % and 9 % Mg doped wollastonite (CSi-6 and CSi-9) and pure or 9 % Mg-rich akermanite (AKT and AKT-9) granules had a gyroid-pore geometry and exhibited different sintering and mechanical properties. The granules were also evaluated on dissolution and osteogenic cell response in vitro and osteogenic capacity in rabbit femoral condylar defect in vivo for different time stages. It was indicated that Mg doping into CSi could contribute appreciable compressive resistance but low bio-dissolution in comparison with the AKT. These silicate bioceramics showed similar osteoblastic viability and the Mg-rich AKT promoted mesenchymal stem cell differentiation in vitro. The surface-curved granules exhibited high-filling networks in the bone defect and promoted bone growth during the early and mid-term stages (40 & 120 days), and especially the wollastonite groups were degraded quickly and akermanite groups stimulated faster bone formation. Taken together, this study demonstrated the potential of Mg-tuning silicate bioceramics in achieving high-efficient bone repair and important implications for optimizing the porous granule fillers design by advanced additive manufacture technique to match the clinical translation with high performance.